In those previously known devices of the type described above, the flexible tube is usually locked by means of specially designed inserts which are adapted to lock the tube against a seat located at the inlet and outlet, respectively. Such inserts are usually mounted on the pump by means of some form of screw joint, and are generally dimensioned such that they can only fit a single tube dimension at a time. Examples of known devices for locking the flexible tube are those shown in U.S. Pat. Nos. 3,791,777 and 4,025,241. In the former case, a plurality of tubes are clasped by means of separate stud bolts 25, and in the latter case the tubes are clasped by means of abutments 104 and 105 with lips 41 and 44 so as to prevent longitudinal movement of the tubing.
A serious drawback with these known inserts is that they must necessarily be exchanged whenever there is a change of tube dimension. Such an exchange is not only time consuming, but it also generally requires some sort of tool in order to loosen the screw joint. Such exchanges are therefore especially troublesome in connection with heart/lung machine pumps, where one is often required to change tube dimensions depending on the desired range of flow.
The object of the present invention is therefore to provide a pump which requires neither an exchange of inserts nor the use of special tools in connection with any change in tube dimension.